ARM: dts: rockchip: enable ARM Mali GPU on rk3288-fennec

Add reference to the Mali GPU device tree node on rk3288-fennec
Tested on Fennec board.
Signed-off-by: NJacob Chen <jacob-chen@iotwrt.com>
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3288-fennec.dts

@@ -99,6 +99,11 @@
 	status = "okay";
 };
 
+&gpu {
+	mali-supply = <&vdd_gpu>;
+	status = "okay";
+};
+
 &hdmi {
 	status = "okay";
 };